Justin Bieber and Selena Gomez Perform ‘Who Says’ Together

Justin Bieber played a show in Rio de Janeiro on Thursday night and he brought a special guest on stage to share a moment with him --  and it was none other than his girlfriend Selena Gomez.

Gomez hopped on stage with her beau during the second of two nights in the city. First, he debuts his new holiday single 'Mistletoe' and then he performs with his girlfriend? Why are all the fans in Rio having all the fun? Not fair, Biebs!

Beforehand, the Biebs teased via Twitter that he would be joined by a guest, posting: "Had a lil fun last night in RIO ... show #2 in RIO is 2nite ... got some very special guests with me 2nite. #Mistletoe."

It wasn't exactly a proper duet, as The Biebs left the stage to let his lady love sing and shine solo. Gomez appeared in her white outfit and sang her hit anthem about self-esteem. The Biebs joined her towards the end of the song – just wait for the screams in the video to get REALLY loud and you'll know that's he's returned to the stage. The twosome sang and jumped up and down together. What a cute and talented couple they are! They hugged twice before the end of the song, with The Biebs saying, "Give it up for Selena Gomez!"

The Biebs tweeted again after the lovebirds shared the stage, writing: "RIO!!! CRAZY!! thanks to @selenagomez for helping me do something special for the crowd. a duet never hurt nobody. WHO SAYS."

Hey Biebs and Selena, bring it to the U.S.!

Watch Justin Bieber and Selena Gomez Perform 'Who Says'